Stabilization of mineral oils



Entente'd Apr. 4, 1944 canes s 2,345,580 smnmzarrouor MINERAL OILS Loran0. Buxton, Belleville, N, 3., asslgnor to N ational Oil ProductsCompany, Harrison, N. 5., a corporation oi New Jersey No Drawing.Application June 21, 1941, Serial No. 399,213

13 Claims.

This invention relates ,in general to the stabilization of mineral oils,and more particularly to the treatment of mineral oils used forlubricating purposes, as constituents of greases, as transformer oils,for, pharmaceutical purposes,

and for other purposes for which mineral oils are adapted so as toinhibit oxidative changes which tend to take place therein.

It is well known that lubricating oils, etc., frequently undergodeteriorative changes on storage or on being heated or exposed to light.This deterioration is due to the presence of components in the oilswhich change in composition as a result of various factors. Althoughthere is some disagreement concerning the exact mechanism of thesevarious changes, it is somewhat generally agreed that the deteriorationis a result of oxidative changes, and that these changes are affected bythe nature of the materials with which the oil comes in contact. As aresult of these oxidative changes, sufficient amounts of deleteriousproducts may be formed as to re der the oil unsafe for future use.Oxidation f the oil may produce organic acids which tend to react withany metal with which the oil is in contact and produce metallic soapsthat are insoluble in the oil. Also various oxidation products of theoil may undergo polymerization or condensation to produce materialsinsoluble in the oil. Any appreciable formation of these variousdeleterious substances may so afiect the properties of the oil so thatit may no longer be efilciently used. In some cases only very minutequantities of oxygen are required to promote undesirable but extensivereactions.

In view of the foregoing and other disadvantages inherent in the use andstorage of mineral oils much work has been done in an attempt to developvarious compounds and materials which may be added to mineral oils andeffectively protect them from deteriorative changes. Although some ofthese additives have proved to have some beneficial action, many of themhave not been entirely satisfactory.

In carrying out experiments relating to the solvent extraction of fattymaterials, I have found that by treating natural antioxidant-containingfatty materials with certain types of organic solvents, highly potentextracts contain-- ing the majority of the natural antioxidants of thefatty material concentrated therein may be obtained. Thus I have foundthat a highly potent antioxidant extract may be obtained from a naturalantioxidant-containing vegetable or fish oil by contacting said oil witha suitable solvent at room temperature or above such that at least themajor portion of the oil is miscible with the solvent and then coolingthe mixture to a temperature within the range of 0 C. to C. whereby asolvent-layer containing the desired antioxidant extract separates.Among thev solvents which were found to be particularly suitable for usein this process are those listed in the table below:

Table I I. Aliphatic and alicyclic monohydroxy alcohols containing from3 to 6 carbon atoms.

2. Esters formed by the reaction of aliphatc and alicyclic alcohols withaliphatic monocarboxylic acids, said esters containing not more than 8carbon atoms.

3. Aliphatic and alicyclic aldehydes contain-- ing not more than 6carbon atoms.

4. Aliphaticketones containing not more than 6 carbon atoms.

It will be noted that these preferred solvents are all liquid organiccompounds having the properties of being substantially miscible withfatty oils at temperatures above room temperatureand partiallyimmiscible therewith at temperatures substantially below roomtemperature; experiments in this connection have shown that solvents ofthis class may be used generally in the process hereinabove described.This process is more'fully described and claimed in my copendingapplication Serial No. 351,909, filed August 8, 1940. I have also foundthat. highly potent antioxidant extracts may be obtained from naturalantioxidant-containing oil-bearing solids, e. g., oil-bearing wheat germmeal, com germ meal, soybean meal, fish meals, etc, by treating thesematerials with solvents by a process similar to that of applicationSerial No. 351,909. The latter process is more fully described andclaimed in copendirfg application Serial No. 397,547, filed June 11,.1941. For further information concerning these processes, reference maybe had to the above-identified applications.

It is an object of this invention to provide a process for treatingmineral oils so as to retard the development of oxidative changestherein.

A more specific object of this invention is to provide mineral oils,particularly lubricating oils, of improved stability.

I have found that the above and other objects of the invention may berealized by the addition to a mineral oil of a relatively smell amountof a natural antioxidant concentrate produced from produced inaccordance with either of the hereinabove identified inventions, or anantioxidant concentrate similar to those produced by the aforementionedprocesses, but produced by other processes.

Any mineral oil or material containing a mineral oil subject todeteriorative oxidative changes may be treated by the process of myinvention. Thus mineral oils used for lubricating purposes, greasescontaining mineral oil, mineral oils used as transformer oils, whitemineral or Russian oils used for pharmaceutical purposes, 1. e., oilssuch as Nujol, etc., may all be protected from oxidative changes by theincorporation therein of the natural antioxidant concentrates. Myantioxidant materials are particularly desirable for treatingpharmaceutical mineral oils which are fortified with vitamin productssuch as vitamin A or other fat-soluble vitamins, as the antioxidantmaterials in addition to protecting the mineral oil from deteriorativeoxidative changes will. also quite effectively protect the vitamins fromdeterioration and oxidation.

It is preferred to use antioxidant concentrates either soybean oil,Wheat germ oil, corn germ oil, cottonseed oil, corn oil, sesame oil,etc., or concentrates produced from either oil-bearing wheat germ meal,oil-bearing corn germ meal, oil-bearing soybean metal, etc., orantioxidant concentrates produced from any mixtures of these,,oi1s oroil-bearing meals; however, it is to be understood that similarantioxidant fractions from any animal or vegetable oil or meal may beused. Furthermore, this invention also covers the use of antioxidantconcentrates similar to those produced by the processes of the twohereinabove identified inventions, but produced by other processes.

In carrying out the process of the invention,

a relatively small amount of a natural antioxidant concentrate may beadmixed with the mineral oil which it is desired to treat. The amount ofantioxidant fraction which is added will depend upon the oil to betreated, the type of deterioration to be prevented, etc. In most casesamounts as low as 0.1% to 0.01% of the weight of the oil to be treatedor even lower are sufiicient. Obviously the amounts which may be usedare not limited to those which are cited as being useful. One skilled inthe art will naturally vary the amounts used so as to obtain the optimumresults.

The antioxidant concentrates used in the process of my invention maywell be used alone for improving the stability of mineral oils; however,if desired, they may be used in combination with other additives whichmay be incorporated into mineral oils for inhibiting deteriorativeoxidative changes. Compounds which'may be used in admixture with thenatural antioxidant concentrates of my invention include hydroxycompounds, such as phenolic derivatives, naphthols, etc.; nitrogencompounds, including naphthylamines, aniline derivatives, etc.; sulfurcompounds as typified by disulfides, thioethers, etc.; and othercompounds useful for improving the stability of mineral oils.

As 'yet the exact chemical composition of the natural antioxidantconcentrates used in the process of my invention has not beendetermined. However, it appears that these antioxidant compositions arenot composed of just one or two antioxidant principles, but rather arecomplex ciples.

mixtures containing several antioxidant prim- Because of the complexityof these concentrates, they are of particular value in that they arethus adapted to protecting mineral oils from more than one type ofdeteriorative oxidative change.-

This application is a continuation-in-part of copending applicationSerial No. 397,547, filed June 11, 1941.

Since certain changes in carrying out the above process and certainmodifications in the composition which embody the invention may be madewithout departing from its scope, it is intended that all mattercontained in the above description shall be interpreted as illustrativeand not in a limiting sense.

It is also to be understood that the followin claims are intended tocover all the generic and specific features of the invention hereindescribed and all statements of the scope of the invention, which as amatter of language, might be said to fall therebetween; and that theyare intended to be inclusive in scope and not exclusive, in that ifdesired, other materials may be added to my novel composition of matterherein claimed without departing from the spirit of the invention.Particularly it is to be understood that in said claims, ingredients orcom ponents recited in the singular are intended to include compatiblemixtures of said ingredients wherever the sense permits.

Having described my invention, what I claim as new and desire to secureby Letters Patent is:

1. A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing material selected from the group consisting ofvegetable oils and vegetable oil-bearing solids at a temperature aboveroom temperature with a solvent'selected from Table I, cooling the massto a temperature within the range of 0 C. to C. whereby layers areformed, separating the solvent layer from the insoluble residue andremoving the extracted natural antioxidant concentrate from the solvent.

2. A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing material selected from the group consisting ofvegetable oils and vegetable oil-bearing solids at a temperature aboveroom temperature with isopropanol, cooling the mass to a temperaturewithin the range of 0 C. to 70 C. whereby layers are formed, separatingthe isopropanol layer from the insoluble residue and removing theextracted natural antioxidant concentrate from the isopropanol.

3. A lubricating oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a'naturalantioxidant-containing material selected from the group consisting ofvegetable oils and vegetable oil-bearing solids at a temperature aboveroom temperature with a solvent selected from Table I, cooling the massto a temperature within the range of 0 C. to -'70 C. whereby layers areformed, separating the solvent layer from the insoluble residue andremoving the extracted natural antioxidant concentrate from the solvent.

4. A lubricating oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing material selected from the group consisting ofvegetable oils and vegetable oil-bearing solids at a temperature aboveroom temperature asaaeso with isopropanol, cooling the mass to atempera= ture within the range of C. to 70 C, whereby layers are formed,separating the isopropanol layer from the insoluble residue and removingthe extracted natural antioxidant concentrate from the isopropanol.

' centrate from the solvent.

6. A mineral oil base lubricating grease stabilined by the presencetherein of a natural antioxidant concentrate prepared by contacting anatural antioxidant-containing material selected from the groupconsisting of vegetable oils and vegetable oil-bearing solids at atemperature above room temperature with a solvent selected from Table I,cooling the mass to a temperature within the range of 0 C. to 'l(l 0.whereby lay= ers are formed, separating the solvent layer from theinsoluble residue and removing the extracted natural antioxidantconcentrate from the solvent.

7. A transformer oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing material selected from the group consisting ofvegetable oils and vegetable oil-bearing solids at a temperature aboveroom temperature with a solvent selected from Table I, cooling the massto a temperature within the range of 0 C, to C. whereby layers areformed, Separating the solvent layer from the insoluble residue andremoving the extracted natural antioxidant conccntrate from the solvent.

8. A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate pred by contacting a natural antioxidant-con-=taming wheat germ oil at a temperature above room temperature with asolvent selected from Table I, cooling the mass to a temperature withinthe range of 0 C. to l0 C. whereby layers are formed; separating thesolvent layer from the ina soluble residue and removing the extractednatural antioxidant concentrate from the solvent.

therein of a natural antioxidant concentrate prepared by contacting anatural antioxldant containing corn germ oil at a temperature above roomtemperature with a solvent selected from Table I, cooling the mass to atemperature within the range of 0 C. to '70 C. whereby layers areformed, separating the solvent layer from the insoluble residue andremoving the extracted natural antioxidant concentrate from the solvent.

10. A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidantcontaining soybean oil at a temperature above roomtemperature with a solvent selected from Table I, cooling the mass to atemperature witl'iin the range of 0 C. to 70 C. whereby layers areformed, separating the solvent layer from the insoluble residue andremoving the extracted natural antioxidant concentrate from the solvent.

11. A. mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidantcontaining wheat germ oil at a temperature above roomtemperature with isopropanol, cooling the mass to a temperature withinthe range of 0? C.

' to -70 0. whereby layers are formed, separating the isopropanol layerfrom the insoluble residue and removing the extracted naturalantioxidant concentrate from the isopropanol.

12, A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing corn germ oil at a temperature above roomtemperature with lsopropanol, cooling the mass to a temperature withinthe range of 0 C. to C. whereby layers are formed, separating theisoprcpanol layer from the insoluble residue and removing the extractednatural antioxidant concentrate from the isopropanol.

13. A mineral oil stabilized by the presence therein of a naturalantioxidant concentrate prepared by contacting a naturalantioxidant-containing soybean oil at a temperature above roomtemperature with isopropanol, cooling the mass to a temperature withinthe range of 0 C. to 70 C. whereby layers are formed, separating theisopropanol layer from the insoluble residue and removing the extractednatural antioxidant concentrate from the isopropanol.

LOR O. BUXTON.

CERTIFICATE OF CORRECTION Patent No. 2,515, 580.

LOHAN o. Buxrorr.

511 l 19th.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 50, for metal'! read --mea1--; page 5, .secondcolumn, line '37, claim 12, for "70 C." read -"(0 '0, u;

and that the said Letters Patent should be read with this correctiontherein that the same may conform to the record of the case in thePatent Office.

(Seal) Leslie Frazer Acting Commissioner of Patents.

9. A mineral oil stabilized by the presence CERTIFICATE or comcrlon.Patent No. 2, 1 580. April 1;, 191 1;.

LORAN o. BUXTON.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 2,first column, line 50, vfor "metal? read --mea1--; page 5, .secondcolumn, line .37 c1a1m 12, for read -70 nd that the ssid Letters Patentshould be read with this correction therein that the same may conform tothe record 01 the case in the Patent Office Signed and sealed this 23rdday of May, A. D. 191 1;.

Les lie Frazer (Seal) Acting commissioner of Patents.

